Abstract

Annealing in S vapor greatly improves the performance of electroplated Cu2ZnSnS4 (CZTS) solar cells based on the bifacial configuration of Al-doped ZnO (AZO, front contact)/ZnO/CdS/CZTS/indium tin oxide (ITO, back contact), as compared to H2S annealing in our previous works. S-vapor annealing does not cause severe damage to the conductivity of the ITO back contact. The highest device efficiency of 5.8% was reached under 1 sun illumination from the AZO side. The well-preformed devices based on the ITO back contact demonstrate smaller series resistances and better fill factors, as compared to our substrate-type devices using Mo back contacts. An interfacial reaction at the ITO back contact has been revealed in experiments, which contributes to the formation of SnO2-enriched interfacial layer and diffusion of In from ITO into CZTS through the Sn sites. Incorporation of In does not significantly change the optical and structural properties or the grain size of CZTS absorbers.

Department of Physics and Astronomy, Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Toledo Ohio 43606 United States

Department of Physics and Astronomy, Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Toledo Ohio 43606 United States; National Renewable Energy Laboratory, Golden CO 80401 United States

@article{osti_1313610,
title = {Improved Performance of Electroplated CZTS Thin-Film Solar Cells with Bifacial Configuration},
author = {Ge, Jie and Yu, Yue and Ke, Weijun and Li, Jian and Tan, Xinxuan and Wang, Zhiwei and Chu, Junhao and Yan, Yanfa},
abstractNote = {Annealing in S vapor greatly improves the performance of electroplated Cu2ZnSnS4 (CZTS) solar cells based on the bifacial configuration of Al-doped ZnO (AZO, front contact)/ZnO/CdS/CZTS/indium tin oxide (ITO, back contact), as compared to H2S annealing in our previous works. S-vapor annealing does not cause severe damage to the conductivity of the ITO back contact. The highest device efficiency of 5.8% was reached under 1 sun illumination from the AZO side. The well-preformed devices based on the ITO back contact demonstrate smaller series resistances and better fill factors, as compared to our substrate-type devices using Mo back contacts. An interfacial reaction at the ITO back contact has been revealed in experiments, which contributes to the formation of SnO2-enriched interfacial layer and diffusion of In from ITO into CZTS through the Sn sites. Incorporation of In does not significantly change the optical and structural properties or the grain size of CZTS absorbers.},
doi = {10.1002/cssc.201600440},
journal = {ChemSusChem},
issn = {1864-5631},
number = 16,
volume = 9,
place = {United States},
year = {2016},
month = {7}
}

Fixed compound parabolic concentrators that couple radiation to solar cells through a prism-shaped dielectric medium were matched to bifacial solar cell arrays. Measures of annual-average short-circuit current output relative to the output with conventional panel operation of the arrays gave optical gains of approximately four times with symmetrical but simulated bifacial arrays and approximately three times with the asymmetrical Westinghouse bifacial arrays. When passive thermosyphon cooling was provided, the power gains measured at peak solar intensity were similar to the optical gains.